1. Technical Field
The present invention relates to a method of forming a carbon nano-tube. More particularly, the present invention relates to a method of forming carbon nano-tubes having relatively high conductivity and high number density.
2. Description of the Related Art
Carbon nano-tubes are cylindrical structures with diameters on the order of nanometers. Because of their unique electrical and physical properties, carbon nano-tubes are the subject of intense research for many applications. One such application is in semiconductor devices. A semiconductor device may be formed using a carbon nano-tube. Examples of methods of forming the semiconductor device that has the carbon nano-tube are disclosed in Korean Patent Laid-open Publication No. 2002-1260, Japanese Patent Laid-open Publication No. 2004-103802, U.S. Patent Application Publication No. 2005-95780 and Korean Patent Laid-open Publication No. 2004-43043.
In the conventional methods, the carbon nano-tube is used as a channel where electrons move. Thus, the more carbon nano-tubes there are in the semiconductor device channel, the greater the reliability of the semiconductor device. Accordingly, a method of forming the carbon nano-tubes capable of increasing the number of carbon nano-tubes per unit area has been widely researched.
In a conventional method of forming the carbon nano-tube, a catalytic film is initially formed on a substrate. A chemical vapor deposition (CVD) process is performed on the catalytic film, so that the catalytic film may be transformed into a plurality of catalytic particles. A CVD process is then performed on the catalytic particle so that a carbon nano-tube may grow from each of the catalytic particles.
However, in the case that a conventional CVD process is employed for forming the carbon nano-tube, the catalytic particles may be combined with one another by thermal dynamic reactions so that the number of catalytic particles may decrease. As a result, the number of carbon nano-tubes each growing from the catalytic particles may also decrease.
In addition, the conventional CVD process is used for forming the carbon nano-tube from the catalytic film, but the conventional CVD process may not be efficiently controllable for growth by stages. The present invention addresses these and other disadvantages of the conventional art.